Bootstrap copied BFF and local accounts with public Sendico contracts (#34)

backend/pkg/merrors/invalid_argument.go

@@ -0,0 +1,44 @@
+package merrors
+
+import (
+	"fmt"
+	"strings"
+)
+
+// InvalidArgumentClassified returns an invalid-argument error with a stable
+// machine reason and structured field names for transport adapters.
+func InvalidArgumentClassified(reason, msg string, argumentNames ...string) error {
+	return classifiedError{
+		base:          ErrInvalidArg,
+		msg:           invalidArgumentMessage(msg, argumentNames...),
+		reason:        strings.TrimSpace(reason),
+		argumentNames: normalizeArgumentNames(argumentNames),
+	}
+}
+
+func invalidArgumentMessage(msg string, argumentNames ...string) string {
+	normalizedNames := normalizeArgumentNames(argumentNames)
+	names := make([]string, 0, len(normalizedNames))
+	for _, name := range normalizedNames {
+		names = append(names, fmt.Sprintf("%q", name))
+	}
+	if len(names) == 0 {
+		return msg
+	}
+
+	prefix := "broken argument"
+	if len(names) > 1 {
+		prefix = "broken arguments"
+	}
+	return fmt.Sprintf("%s %s: %s", prefix, strings.Join(names, ", "), msg)
+}
+
+func normalizeArgumentNames(argumentNames []string) []string {
+	names := make([]string, 0, len(argumentNames))
+	for _, name := range argumentNames {
+		if name = strings.TrimSpace(name); name != "" {
+			names = append(names, name)
+		}
+	}
+	return names
+}